There is no universal maximum speed for a reject conveyor. Capacity depends on belt speed, minimum pack pitch, product stability, the reject device’s actuation and recovery time, the distance available for separation and the response required after an unverified reject. The design must be proven with the real product range at the agreed operating conditions.
Throughput without guesswork
What determines how fast a reject conveyor can run?
Products per minute is only one part of the duty. Two lines can run at the same rate but present very different rejection problems: one may have a generous gap between rigid cartons, while the other has flexible packs almost touching on a faster belt. The second application gives the reject device far less time to act without disturbing a good product.
Oxford Vision Systems reviews maximum and minimum pack length, actual pitch, conveyor speed, speed variation, product slip and the distance from inspection to rejection. This establishes the available timing window and whether time-based or encoder-based tracking is appropriate.
Actuation, recovery and the next product
An air blast can complete a short non-contact action, while a pusher, sweep arm, flap or retracting belt must also return to its safe home position. The next product cannot enter the reject zone until the mechanism and product path are ready. Consecutive reject conditions therefore need to be considered separately from normal production rate.
The receiving chute or bin matters too. A product that leaves the main belt but rebounds, bridges the chute or obstructs the next reject has not been handled successfully. Trials should observe the complete trajectory, including the lightest, heaviest and least stable products.
Tracking at variable conveyor speed
Where belt speed can change, encoder-based tracking can maintain the relationship between the inspection decision and physical product movement. Photoelectric sensors may be used to establish pack edges, pitch or entry into the reject zone. The control method is selected around the conveyor, drive and likelihood of products slipping or accumulating.
Independent reject confirmation then checks the outcome. A missing confirmation, mechanism-not-home signal, low air condition or full bin can initiate the agreed alarm, controlled stop or production lockout.
How to specify a high-speed trial
Define the full product matrix and test at agreed minimum and maximum speeds. Include minimum pitch, deliberate consecutive failures, start-up, controlled speed changes and the fault states that could invalidate rejection. This produces useful acceptance criteria instead of relying on an unqualified headline rate.
Key project considerations
- Minimum and maximum pack pitch
- Variable-speed conveyor tracking
- Consecutive reject handling
- Actuator home-position monitoring
- Independent reject confirmation
- Product trials at agreed line conditions